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          <th colspan="3" align="center">DB-&gt;close()</th>
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          <td width="20%" align="left"><a accesskey="p" href="dbassociate_foreign.html">Prev</a> </td>
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                The DB Handle
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    <div class="sect1" lang="en" xml:lang="en">
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          <div>
            <h2 class="title" style="clear: both"><a id="dbclose"></a>DB-&gt;close()</h2>
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      <pre class="programlisting">#include &lt;db.h&gt;

int
DB-&gt;close(DB *db, u_int32_t flags);  </pre>
      <p>
         The <code class="methodname">DB-&gt;close()</code> method flushes cached database information to
         disk, closes any open cursors, frees allocated resources, and
         closes underlying files. When the close operation for a cursor fails, 
         the method returns a non-zero error value for the first instance of such an error, 
         and continues to close the rest of the cursors and database handles.
    </p>
      <p>
         Although closing a database handle will close any open cursors, it
         is recommended that applications explicitly close all their
         <a class="link" href="dbc.html" title="Chapter 3.  The DBcursor Handle">DBcursor</a> handles
         before closing the database. The reason why is that when
         the cursor is explicitly closed, the memory allocated for it is
         reclaimed; however, this will <span class="emphasis"><em>not</em></span> happen if
         you close a database while cursors are still opened.
     </p>
      <p>
         The same rule, for the same reasons, hold true for 
         <a class="link" href="txn.html" title="Chapter 12.  The DB_TXN Handle">DB_TXN</a>
         handles. Simply make sure you close all your transaction handles
         before closing your database handle.
     </p>
      <p>
         Because key/data pairs are cached in memory, applications should
         make a point to always either close database handles or sync their
         data to disk (using the <a class="xref" href="dbsync.html" title="DB-&gt;sync()">DB-&gt;sync()</a> 
         method) before exiting, to ensure that any data cached in main memory are
         reflected in the underlying file system.
    </p>
      <p>
         When called on a database that is the primary database for a secondary
         index, the primary database should be closed only after all secondary
         indices referencing it have been closed.
    </p>
      <p>
             When multiple threads are using the <a class="link" href="db.html" title="Chapter 2.  The DB Handle">DB</a>
             concurrently, only a single thread may call the <code class="methodname">DB-&gt;close()</code> method.
    </p>
      <p>
         The <a class="link" href="db.html" title="Chapter 2.  The DB Handle">DB</a>  handle may not be
         accessed again after <code class="methodname">DB-&gt;close()</code> is called, regardless of its return.
    </p>
      <p>
     	If you do not close the <a class="link" href="db.html" title="Chapter 2.  The DB Handle">DB</a> handle explicitly, it will be closed when
     	the environment handle that owns the <a class="link" href="db.html" title="Chapter 2.  The DB Handle">DB</a> handle is closed.
    </p>
      <p>
         The <code class="methodname">DB-&gt;close()</code> <span>
            <span>
                  method returns a non-zero error value on failure and 0 on success.
            </span>
            
        </span>
         The error values that <code class="methodname">DB-&gt;close()</code> method returns include the error values of <code class="methodname">DBcursor-&gt;close()</code> and the following:
    </p>
      <div class="sect3" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h4 class="title"><a id="idp49255952"></a>DB_LOCK_DEADLOCK</h4>
            </div>
          </div>
        </div>
        <p>
                A transactional database environment operation was selected to resolve
                a deadlock.
            </p>
      </div>
      <div class="sect3" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h4 class="title"><a id="idp49273128"></a>DB_LOCK_NOTGRANTED</h4>
            </div>
          </div>
        </div>
        <p>
                A Berkeley DB Concurrent Data Store database environment configured
                for lock timeouts was unable to grant a lock in the allowed time.
            </p>
        <p>
                You attempted to open a database handle that is configured
                for no waiting exclusive locking, but the exclusive lock could not be
                immediately obtained. See
                <a class="xref" href="dbset_lk_exclusive.html" title="DB-&gt;set_lk_exclusive()">DB-&gt;set_lk_exclusive()</a>
                for more information.
            </p>
      </div>
      <div class="sect3" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h4 class="title"><a id="idp49252240"></a>EINVAL</h4>
            </div>
          </div>
        </div>
        <p>
                If the cursor is already closed; or if an invalid flag value or parameter was specified.
            </p>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp49378640"></a>Parameters</h3>
            </div>
          </div>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp49378832"></a>flags</h4>
              </div>
            </div>
          </div>
          <p>
                          The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
                          or be set to the following value:
                     </p>
          <div class="itemizedlist">
            <ul type="disc">
              <li>
                <p><a id="dbclose_DB_NOSYNC"></a>
                          <code class="literal">DB_NOSYNC</code>
                    </p>
                <p>
                         Do not flush cached information to disk.  This flag is a
                         dangerous option. It should be set only if the application is doing
                         logging (with transactions) so that the database is recoverable after
                         a system or application crash, or if the database is always generated
                         from scratch after any system or application crash.
                    </p>
                <p>
                         <span class="bold"><strong>It is important to understand that flushing
                         cached information to disk only minimizes the window of opportunity
                         for corrupted data.</strong></span> Although unlikely, it is possible for
                         database corruption to happen if a system or application crash occurs
                         while writing data to the database.  To ensure that database
                         corruption never occurs, applications must either: use transactions
                         and logging with automatic recovery; use logging and
                         application-specific recovery; or edit a copy of the database, and
                         once all applications using the database have successfully called
                         <code class="methodname">DB-&gt;close()</code>, atomically replace the original database with the
                         updated copy.
                    </p>
                <p>
                        Note that this flag only works when the database
                        has been opened using an environment. 
                    </p>
              </li>
            </ul>
          </div>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp49382496"></a>Errors</h3>
            </div>
          </div>
        </div>
        <p>
            The <code class="methodname">DB-&gt;close()</code> <span>
            <span>
                 method may fail and return one of the following non-zero errors:
            </span>
            
        </span>
        </p>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp49387736"></a>EINVAL</h4>
              </div>
            </div>
          </div>
          <p>
                An invalid flag value or parameter was specified.
            </p>
        </div>
        <p>
	The error messages returned for the first error encountered when <code class="methodname">DB-&gt;close()</code> method closes any open cursors include:
	</p>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp49360320"></a>DB_LOCK_DEADLOCK</h4>
              </div>
            </div>
          </div>
          <p>
                A transactional database environment operation was selected to resolve
                a deadlock.
            </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp49385048"></a>DB_LOCK_NOTGRANTED</h4>
              </div>
            </div>
          </div>
          <p>
                A Berkeley DB Concurrent Data Store database environment configured
                for lock timeouts was unable to grant a lock in the allowed time.
            </p>
          <p>
                You attempted to open a database handle that is configured
                for no waiting exclusive locking, but the exclusive lock could not be
                immediately obtained. See
                <a class="xref" href="dbset_lk_exclusive.html" title="DB-&gt;set_lk_exclusive()">DB-&gt;set_lk_exclusive()</a>
                for more information.
            </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp49390696"></a>EINVAL</h4>
              </div>
            </div>
          </div>
          <p>
                If the cursor is already closed; or if an invalid flag value or parameter was specified.
            </p>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp49390400"></a>Class</h3>
            </div>
          </div>
        </div>
        <p>
                <a class="link" href="db.html" title="Chapter 2.  The DB Handle">DB</a>  
            </p>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp49392336"></a>See Also</h3>
            </div>
          </div>
        </div>
        <p>
            <a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a> 
        </p>
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